 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.texteditor.quickdiff.compare.rangedifferencer;

 /**
  * For breaking an object to compare into a sequence of comparable entities.
  * <p>
  * It is used by <code>RangeDifferencer</code> to find longest sequences of
  * matching and non-matching ranges.
  * <p>
  * For example, to compare two text documents and find longest common sequences
  * of matching and non-matching lines, the implementation must break the document
  * into lines. <code>getRangeCount</code> would return the number of lines in the
  * document, and <code>rangesEqual</code> would compare a specified line given
  * with one in another <code>IRangeComparator</code>.
  * </p>
  * <p>
  * Clients should implement this interface; there is no standard implementation.
  * </p>
  *
  * @since 3.0
  */
 public interface IRangeComparator {

     /**
      * Returns the number of comparable entities.
      *
      * @return the number of comparable entities
      */
     int getRangeCount();

     /**
      * Returns whether the comparable entity given by the first index
      * matches an entity specified by the other <code>IRangeComparator</code> and index.
      *
      * @param thisIndex the index of the comparable entity within this <code>IRangeComparator</code>
      * @param other the IRangeComparator to compare this with
      * @param otherIndex the index of the comparable entity within the other <code>IRangeComparator</code>
      * @return <code>true</code> if the comparable entities are equal
      */
     boolean rangesEqual(int thisIndex, IRangeComparator other, int otherIndex);

     /**
      * Returns whether a comparison should be skipped because it would be too costly (or lengthy).
      *
      * @param length a number on which to base the decision whether to return
      * <code>true</code> or <code>false</code>
      * @param maxLength another number on which to base the decision whether to return
      * <code>true</code> or <code>false</code>
      * @param other the other <code>IRangeComparator</code> to compare with
      * @return <code>true</code> to avoid a too lengthy range comparison
      */
     boolean skipRangeComparison(int length, int maxLength, IRangeComparator other);
 }

